AgResearch finds pasture pests costing economy billions

Pests most commonly targeting New Zealand’s pastures are costing the economy up to $2.3 billion a year, an AgResearch study has found.

The study is the first of its kind to estimate the financial impact of invertebrate pests such as the grass grub, black beetle, nematodes and weevils in terms of lost productivity for pastoral farming.

The full science paper has been published this week in the New Zealand Journal of Agricultural Research and can be found HERE.

Of the total estimated annual losses of between $1.7 billion and $2.3 billion in `average’ years, up to $1.4b billion occurs on dairy farms, and up to $900 million on sheep and beef farms.

“Our research shows that the impact of the grass grub alone costs dairy farms up to $380 million, and sheep and beef farms up to $205 million, each year,” says AgResearch scientist Colin Ferguson.

Losses attributable to these pasture pests are usually determined either on the basis of the amount of foliage they consume, or reductions in pasture production.

However, AgResearch’s study has used the reduction in pasture production to estimate the impact on milk production revenue for dairy farms, and on meat production revenue for sheep and beef farms.

“What this provides us is a good picture of the challenge we and farmers face with pasture pests, and it reinforces the need to invest in new and cost-effective ways to better control these pests,” Mr Ferguson says.

“AgResearch is looking at pest control on a number of fronts, including the development of new biopesticides – naturally occurring organisms that can be used to target specific pest species, instead of chemical treatments that can be expensive and have unwanted impacts on the environment.”

The study was initiated as part of Pastoral 21 Next Generation Dairy Systems and funded by DairyNZ, Fonterra, Dairy Companies Association of New Zealand, Beef + Lamb New Zealand and MBIE – and has been completed with funding from AgResearch.

Source: AgResearch

Drive is under way to rid communities of wasps

Invasive “social” wasps are putting major pressure on New Zealand’s biodiversity and cost the economy an estimated $130 million a year, Radio NZ reminded us today.

That figure comes from a 2015 Department of Conservation study (HERE) which assessed the economic impact of German wasps and common wasps across industries, society and the natural environment in New Zealand.

The report said the biggest economic impacts were on farming, beekeeping, horticulture and forestry workers.

This assessment was based on a literature review. Information was collected from previous studies and from affected sectors in New Zealand to estimate the total costs of wasps, ie the costs that could be avoided and the opportunities that could be gained if wasps were not present in New Zealand.

New Zealand has some of the highest densities of German and common wasps in the world. Wasps have huge social and biological impacts; they are one of the most damaging invertebrate pests in New Zealand, harming our native birds and insects.

The DOC study found the major financial impact was on primary industries and the health sector and included:

  • more than $60 million a year in costs to pastoral farming from wasps disrupting bee pollination activities, reducing the amount of clover in pastures and increasing fertiliser costs.
  • almost $9 million a year cost to beekeepers from wasps attacking honey bees, robbing their honey and destroying hives.
  • wasp-related traffic accidents estimated to cost $1.4 million a year.
  • over $1 million each year spent on health costs from wasp stings.
  • on top of the direct costs, almost $60 million a year is lost in unrealised honey production from beech forest honeydew which is currently being monopolised by wasps. Honeydew is also a valuable energy source for kaka, tui and bellbirds.

Radio NZ today described the invasive common wasp (aka Vespula Vulgaris), the German wasp, and our three species of paper wasp as being among “our most-hated introduced pests”.

The Royal Society, the Department of Conservation and some local communities are dedicating time, money and energy into putting an end to their predatory behaviour, which affects birds, bats, bees and other insects.

Entomologist and author of The Vulgar Wasp Phil Lester has been talking with Simon Morton about New Zealand’s problem wasps and the latest ways of keeping them under control, which include insecticides and genetic manipulation.

You can listen here to the interview (duration15′ :02″)

Source: Radio NZ

Initial successes reported after the release of rabbit-killing virus in Otago

A new virus introduced to fight plagues of the rabbit pest in Otago is taking effect, Radio New Zealand reports (HERE).

Field samples from the Otago Regional Council showed the K5 strain of the rabbit haemorrhagic disease is killing its targets.

The council’s director environmental monitoring and operations, Scott MacLean,  welcomed the initial data but cautioned that the virus will not be widespread yet.

It will continue to spread for 12 to 14 weeks, he said.  Land owners should plan secondary controls for winter.

Reporting earlier this year on the release of the rabbit virus across the country, including 100 sites in Otago, Stuff said officials hoped to kill more than 40 per cent of the pest population.

The Stuff report (HERE) explained that the K5 virus is a Korean variant of a strain that is already in New Zealand, after it was illegally released here in 1997 by a collective of vigilante Otago farmers.

Mr MacLean told Stuff at that time the approval of K5 was good news.

“Rabbits are the number one pest in Otago. Ten rabbits can eat as much grass as one sheep. They are a threat to our biodiversity, not to mention the soil degradation and loss of soil caused by rabbit holes and warrens.

“The K5 virus, which only affects the European rabbit, may give us the opportunity to reduce rabbit numbers to the level where they are manageable. It will be especially beneficial in areas where traditional rabbit management methods are either not possible or not acceptable.”

Environment Canterbury applied in November to the Ministry for Primary Industries for approval to introduce and use the Rabbit Haemorrhagic Virus Disease RHDV1-K5 for pest rabbit management.

ECan regional leader biosecurity Graham Sullivan said the virus would be released in March and April, but would not eradicate the population.

“While not the silver bullet for rabbit control, we anticipate that the new strain will greatly assist the control of wild rabbit populations by supplementing more traditional control methods.

“The controlled release will use a high-quality commercially prepared product at selected sites identified by participating local councils.”

The virus would be spread nationally in a coordinated programme. There would be more than 100 release sites in Otago and the council would coordinate the release to make sure it had maximum impact, MacLean said.

“These sites were selected based on science to ensure we have the best chance of creating an epidemic and a high knock-down (kill) rate.”

The virus is not being introduced without opposition.

Rabbit Council of New Zealand member Gary Stephenson, who submitted against ECan’s application, feared rabbit owners had not been given enough time to get their animals vaccinated against the “abhorrent” virus.

“There are thousands of rabbit owners up in arms and really, really worried about this … The pet rabbit population deserves the same care and protections from government and the animal welfare rights [groups] as pet cats and dogs … There are many other means of controlling wild rabbits that do not threaten pet rabbits or treat pet rabbits as collateral damage.

“I have been fighting this since June 2015 … It’s absolutely abhorrent.”

Mr Stephenson said it took 21 days for a vaccination to be effective, which did not give pet rabbit owners much time.

Rabbits infected with K5 develop symptoms between 24 hours and 72 hours after infection and usually die within six hours to 36 hours after the first symptoms appear.

More information can be found on the Ministry for Primary Industries’ website HERE. 

“Quiet forest” claims are dispelled by bioacoustics study of 1080 effects

The use of the toxin sodium monofluoroacetate (otherwise known as 1080) for possum eradication has long raised concerns that a heavy toll is being taken on wildlife and the environment.

The Department of Conservation – supported by farm organisations among others – says it is the most suitable poison for aerial drops to kill possums which are destroying native bush. Destroying possums limits the spread of tuberculosis from the pests to livestock on farms.

But 1080’s critics say the poison kills not only pests, but also native birds and wildlife such as kiwi. Moreover, it is a cruel method of pest control and may contaminate the ground and waterways.

On  Radio New Zealand’s Nine to Noon programme this morning, Roald Bomans told of studies to investigate the claim that aerial 1080 drops cause forests to fall silent.

He used bioacoustics, a developing area in ecology, to monitor native bird species in the Remutaka and Aorangi Ranges.

He did this by listening to recordings and developing a special detector for morepork calls.

Collectively his bioacoustic monitoring showed no negative impact on the populations of native bird species.

The interview can be heard HERE.

It follows a seminar led by Roald Bomans at Victoria University last month.

According to his notes on the university website (HERE) about the seminar :

I used recordings from autonomous recording units (ARUs) to monitor resident bird species over multiple aerial 1080 operations in order to investigate this claim.

The total amount of birdsong recorded did not decrease significantly in treatment areas relative to non-treatment areas. The calling prevalence of one species, the introduced chaffinch (

Diurnal monitoring was conducted for 10-12 weeks over two independent operations. The total amount of birdsong recorded did not decrease significantly in treatment areas relative to non-treatment areas. The calling prevalence of one species, the introduced chaffinch (Fringilla coelebs), showed a significant decline in the treatment area across one of the two operations monitored. Collectively, these results suggested no negative impact of modern 1080 operations on the populations of native bird species.

Extracting data from ARU recordings can be labour intensive.

In the second part of my study I developed a process for developing a parsimonious template-based detector in an efficient, objective manner and applied this method to the creation of a detector for morepork (Ninox novaeseelandiae) calls.  The method was highly successful as a directed means to achieve parsimony. In independent validation tests, the final detector had a high precision (0.939) and moderate sensitivity (0.399).

This detector was used to monitor morepork in treatment and non-treatment areas across three independent aerial 1080 operations. Morepork showed no significant difference in trends of calling prevalence across the three operations monitored. Over a longer time period, a significant quadratic effect of time since 1080 treatment was found, with calling prevalences predicted to increase for 3.5 years following treatment.

Collectively, the results suggest a net-positive effect of modern 1080 mammal control on morepork populations.




Decades-old DNA match aids battle against pasture pests

AgResearch research associate Nicky Richards and her colleagues, recently confronted with a Porina (Wiseana) caterpillar found in Southland, were challenged with identifying which species of the pasture-munching Porina pest they were looking at.

Some species of Porina pose a much greater threat to pasture on New Zealand farms than others. Although seven Porina species are recognised, and the species can be identified by sight at the adult moth stage, it is impossible to do the same with the caterpillars because they look identical.

The research team suspected the caterpillar found in Southland was from an elusive Porina species known as Wiseana (W.) fuliginea.

To confirm this they needed to analyse an adult moth of the same species.

Mrs Richards explains:

“Unfortunately, no adult W. fuliginea had been found by us in our previous 20 years of field collections. So we had to find another way. Our connections led us to museum specimens held in the New Zealand Arthropod Collection hosted by Landcare Research. There we found dried adult W. fuligineaspecimens that had been identified and preserved after their deaths 33 years ago.”

“We took legs from these long-dead moths to generate genetic sequences – which takes more work when the DNA has broken down over time. It’s basically like putting together pieces of overlapping Lego to build what you need.”

Information gleaned from the 33-year-old specimens proved identical to the sequence from the caterpillar found in Southland. In other words, the researchers had a DNA match.

The work has helped in the development of a new DNA-based method to identify Porina caterpillars. By building a better understanding of this pest, scientists can learn how best to help farmers prevent the hundreds of millions of dollars of damage it can do to pasture on New Zealand’s farms each year.

Environmentally friendly treatments for Porina outbreaks can be explored and species that are the key pasture annihilators targeted, Richards said.

More can be learned about Porina and other pests at

Good news for bees? Varroa mites have genetic holes in their armour

Seemingly indestructible Varroa mites have decimated honeybee populations and are a primary cause of colony collapse disorder, or CCD.

Zachary Huang, an entomologist at Michigan State University, describes the mite is the greatest threat to honeybee health worldwide,

“They have developed resistance to many pesticides, so it’s urgent that we explore and target these genes to develop better control methods.”

A promising development is the discovery by MSU scientists of genetic holes in the pests’ armour that could potentially reduce or eliminate the marauding invaders.

The team’s results, published in the current issue of Insect Science, have identified four genes critical for survival and two that directly affect reproduction.

The mite sucks the blood of honeybees and transmits deadly viruses. Its lifecycle consists of two phases: one where they feed on adult bees (the phoretic phase) and a reproductive phase that takes place within a sealed honeycomb cell, where the mites lay eggs on a developing bee larva.

The double-whammy of eating bees and spreading disease makes Varroa mites the number-one suspect of honeybee population declines worldwide.

Controlling such pests depends on either eliminating them or reducing their ability to reproduce. The MSU team used RNA interference to identify the key genes, which could achieve these outcomes. They injected the mites with double-stranded RNA, or dsRNA.

Interfering reduces transcription of a specific gene, the first step of making a gene, a piece of DNA, into a protein. This process, also known as “gene knockdown,” has been successful in reducing the mating success and the number of eggs produced by cattle ticks, which threaten cows and other livestock around the world.

Using this approach, the team identified two genes that caused high mortality in Varroa mites — Da and Pros26S. In fact, Da killed more than 96 percent of mites. They also identified four genes — RpL8, RpL11, RpP0 and RpS13 — that control reproduction.

Earlier research has shown that a combination of dsRNAs can be fed to bees at the colony level. Varroa mites absorb the “genetic cocktail” via bee blood and their population was reduced. Future research will explore whether a single-gene approach can be scaled up and achieve the same effect at a colony-wide setting. Using a single gene with a known mechanism will be more cost effective and safe to the honeybees.

The results may have applications beyond honeybees, too.

“It’s worth noting that Da reduced reproduction in species of mosquitoes and Drosophila,” Huang said.

Future research could help not only protect honeybees, but also reduce disease-carrying mosquitoes or crop-damaging pests, he said.

Huge savings estimated from wasp introduced to curb clover root weevil

A humble Irish wasp has saved New Zealand almost half a billion dollars, AgResearch estimates.

The estimates also show that the benefits of the introduction of the wasp by AgResearch to control the highly destructive clover root weevil are expected to continue at an ongoing rate of at least $158 million a year.

The total benefit of the biological control programme from 2006 – when the imported wasp was first released in an experimental phase – through to this year is estimated at at least $489m. This is based on reduced production losses on sheep and beef farms, and reduced use of urea fertiliser to compensate for damage from the weevil.

“It’s a fantastic example of how our science is making a real and profound difference to our agricultural sector and economy,” says AgResearch Science Team Leader Alison Popay.

“It’s also a real success story in the continuing battle against pests on New Zealand’s farms.”

The clover root weevil, an invasive pest from the northern hemisphere which feeds on clover, was first detected in New Zealand in 1996. A 2005 study estimated that without control it could cut farm margins by 10 to 15 per cent.

AgResearch started a research and development programme in 1996, and after testing to ensure its safety, the Irish wasp was cleared for release in New Zealand in 2005. It spread around the country with releases by AgResearch, and as wasps were provided to farmers.

The programme research and development costs have been about $8.2 million.

The wasp injects its eggs in the adult root weevil, and the resulting grubs inside the weevil render it infertile. Once fully grown, the grub kills the weevil as it eats its way out. One wasp can kill about 85 clover root weevils.

“The wasp was so successful the team found that it reduced weevil populations by around 90 per cent in monitored areas where the wasp is well established,” Dr Popay says.

The control programme has been supported by DairyNZ, Beef + Lamb New Zealand, Federated Farmers, the Clover Root Weevil Action group, the New Zealand Landcare Trust and fertiliser companies.